From aaf0d2c49f343e909dc69b487056ca31238ffabf Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@airbus.com>
Date: Thu, 21 Mar 2019 16:04:16 +0100
Subject: [implem-python] Nettoyage PEP8
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- espaces avant ':'
- espaces en trop après ','
- parenthèses dans les if
- levée d'exception plutôt que 'return None' implicite

Simplification  de genkat_aead.py  grâce  à l'exception  levée par  le
module.
---
 python/lilliput_ae_1.py | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

(limited to 'python/lilliput_ae_1.py')

diff --git a/python/lilliput_ae_1.py b/python/lilliput_ae_1.py
index 8b618d9..9aad3a6 100644
--- a/python/lilliput_ae_1.py
+++ b/python/lilliput_ae_1.py
@@ -11,6 +11,7 @@ from helpers import (
     BlockbytesMatrixToBytes,
     BuildAuth,
     Padding10LSB,
+    TagValidationError,
     XorState
 )
 
@@ -19,23 +20,23 @@ TWEAK_BITS = 192
 TWEAK_BYTES = TWEAK_BITS//8
 
 
-def LowPart(array, number_bits) :
+def LowPart(array, number_bits):
     shifted = 0
-    for byte in range(0, len(array)) :
+    for byte in range(0, len(array)):
         shifted |= (array[byte] << (8 * byte))
 
     mask = 0
-    for bit in range(0, number_bits) :
+    for bit in range(0, number_bits):
         mask |= (0x1 << bit)
 
     lower_part = shifted & mask
 
     will_padd = 0
-    if (number_bits % 8) != 0 :
+    if number_bits % 8 != 0:
         will_padd = 1
 
-    lower_part_byte = [0 for byte in range(0, int(number_bits / 8)  + will_padd)]
-    for byte in range(0, int(number_bits / 8)  + will_padd) :
+    lower_part_byte = [0 for byte in range(0, int(number_bits / 8) + will_padd)]
+    for byte in range(0, int(number_bits / 8) + will_padd):
         lower_part_byte[byte] = lower_part & 0xff
         lower_part = lower_part >> 8
 
@@ -50,13 +51,13 @@ class _MessageTweak(Enum):
 
 
 def TweakMessage(N, j, padding):
-    tweak = [0 for byte in range(0,  TWEAK_BYTES)]
-    for byte in range(NONCE_BYTES-1, -1, -1) :
+    tweak = [0 for byte in range(0, TWEAK_BYTES)]
+    for byte in range(NONCE_BYTES-1, -1, -1):
         tweak[byte + (TWEAK_BYTES-NONCE_BYTES)] |= (N[byte] & 0xf0) >> 4
         tweak[byte + (TWEAK_BYTES-NONCE_BYTES-1)] |= (N[byte] & 0x0f) << 4
 
     tweak[TWEAK_BYTES-NONCE_BYTES-1] |= ((j >> 64) & 0xf)
-    for byte in range(TWEAK_BYTES-NONCE_BYTES-2, -1, -1) :
+    for byte in range(TWEAK_BYTES-NONCE_BYTES-2, -1, -1):
         tweak[byte] = (j >> (8 * byte)) & 0xff
 
     tweak[-1] |= padding.value<<4
@@ -96,7 +97,7 @@ def TreatMessageEnc(M, N, key):
     return (Final, C)
 
 
-def TreatMessageDec(C, N, key) :
+def TreatMessageDec(C, N, key):
     checksum = [0 for byte in range(0, BLOCK_BYTES)]
 
     l = len(C)//BLOCK_BYTES
@@ -129,7 +130,7 @@ def TreatMessageDec(C, N, key) :
 
 
 ################################################################################
-def encrypt(A, M, N, key) :
+def encrypt(A, M, N, key):
     K = list(key)
 
     Auth = BuildAuth(TWEAK_BITS, A, K)
@@ -139,7 +140,7 @@ def encrypt(A, M, N, key) :
     return BlockbytesMatrixToBytes(C), bytes(tag)
 
 
-def decrypt(A, C, N, tag, key) :
+def decrypt(A, C, N, tag, key):
     K = list(key)
     tag = list(tag)
 
@@ -147,5 +148,7 @@ def decrypt(A, C, N, tag, key) :
     (Final, M) = TreatMessageDec(C, N, K)
     tag2 = XorState(Auth, Final)
 
-    if(tag == tag2) :
-        return BlockbytesMatrixToBytes(M)
+    if tag != tag2:
+        raise TagValidationError(tag, tag2)
+
+    return BlockbytesMatrixToBytes(M)
-- 
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